共查询到20条相似文献,搜索用时 74 毫秒
1.
Chudalla R Baerwalde S Schneider G Maassen N 《Pflügers Archiv : European journal of physiology》2006,452(6):690-697
To evaluate the relationship between lactate release and [lac]art and to investigate the influence of the catecholamines on the lactate release, 14 healthy men [age 25±3 (SE) year] were studied by superimposing cycle on forearm exercise, both at 65% of their maximal power reached in respective incremental tests. Handgrip exercise was performed for 30 min at 65% of peak power. In addition, between the tenth and the 22nd minute, cycling with the same intensity was superimposed. The increase in venous lactate concentration ([lac]ven) (rest: 1.3±0.4 mmol·l−1; 3rd min: 3.9±0.8 mmol·l−1) begins with the forearm exercise, whereas arterial lactate concentration ([lac]art) remains almost unchanged. Once cycling has been added to forearm exercise (COMB), [lac]art increases with a concomitant increase in [lac]ven (12th min: [lac]art, 3.2±1.3 mmol·l−1; [lac]ven, 5.7±2.2 mmol·l−1). A correlation between oxygen tension (PvO2) and [lac]ven cannot be detected. There is a significant correlation between [lac]art and norepinephrine ([NE]) (y=0.25x+1.2; r=0.815; p<0.01) but no correlation between lactate release and epinephrine ([EPI]) at moderate intensity. Our main conclusion is that lactate release from exercising muscles at moderate intensities is neither dependent on PvO2 nor on [EPI] in the blood. 相似文献
2.
Plasma vasopressin,renin activity,and aldosterone responses to maximal exercise in active college females 总被引:1,自引:0,他引:1
Summary The effect of maximal treadmill exercise on plasma concentrations of vasopressin (AVP); renin activity (PRA); and aldosterone
(ALDO) was studied in nine female college basketball players before and after a 5-month basketball season. Pre-season plasma
AVP increased (p<0.05) from a pre-exercise concentration of 3.8±0.5 to 15.8±4.8 pg · ml−1 following exercise. Post-season, the pre-exercise plasma AVP level averaged 1.5±0.5 pg · ml−1 and increased to 16.7±5.9 pg · ml−1 after the exercise test. PRA increased (p<0.05) from a pre-exercise value of 1.6±0.6 to 6.8±1.7 ngAI · ml−1 · hr−1 5 min after the end of exercise during the pre-season test. In the post-season, the pre-exercise PRA was comparable (2.4±0.6
ngAI · ml−1 · hr−1), as was the elevation found after maximal exercise (8.3±1.9 ngAI · ml−1 · hr−1). Pre-season plasma ALDO increased (p<0.05) from 102.9±30.8 pg · ml−1 in the pre-exercise period to 453.8±54.8 pg · ml−1 after the exercise test. In the post-season the values were 108.9±19.4 and 365.9±64.4 pg · ml−1, respectively. Thus, maximal exercise in females produced significant increases in plasma AVP, renin activity, and ALDO that
are comparable to those reported previously for male subjects. Moreover, this response is remarkably reproducible as demonstrated
by the results of the two tests performed 5 months apart. 相似文献
3.
The effect of sodium bicarbonate and sodium citrate ingestion on anaerobic power during intermittent exercise 总被引:1,自引:0,他引:1
Summary The effect of sodium bicarbonate and sodium citrate ingestion on cycling performance in three 30 s Wingate Anaerobic Tests
separated by 6 min recovery periods has been studied using 6 male subjects. Subjects ingested either sodium bicarbonate (B),
sodium bicarbonate plus sodium citrate (BC), sodium citrate (C) or sodium chloride (P) 2.5 h prior to exercise in a dose of
0.3 g kg−1 body weight. Pre-exercise blood pH was 7.44±0.06, 7.42±0.05, 7.41±0.05 and 7.38±0.04 in the C, BC, B and P conditions respectively.
Mean and peak power output were significantly reduced by successive Wingate tests but not significantly affected by the treatments.
Performance in the second and third tests was highest following C, BC and B ingestion. The total work done in the 3 tests
was 103%, 102% and 101% of that achieved in the P condition after C, BC and B ingestion respectively. The increased alkali
reserve recorded subsequent to bicarbonate and citrate treatment reduced mean post-exercise acidosis, although pH was significantly
higher only in the C condition (p<0.05) compared to P after each exercise bout. No significant differences in plasma lactate concentration were recorded at
any time. Citrate ingestion appears to be most effective in elevating blood pH and [HCO3
−], and in enhancing performance in short-term intermittent exercise. This study demonstrates that alkali ingestion results
in significant shifts in the acid-base balance of the blood and has a small, but non-significant, effect on anaerobic power
and capacity as measured in a series of 3 Wingate Anaerobic Tests. 相似文献
4.
Jamie Stanley Michael Leveritt Jonathan M. Peake 《European journal of applied physiology》2010,110(6):1163-1173
We compared the effects of an ice-slush beverage (ISB) and a cool liquid beverage (CLB) on cycling performance, changes in
rectal temperature (T
re) and stress responses in hot, humid conditions. Ten trained male cyclists/triathletes completed two exercise trials (75 min
cycling at ~60% peak power output + 50 min seated recovery + 75% peak power output × 30 min performance trial) on separate
occasions in 34°C, 60% relative humidity. During the recovery phase before the performance trial, the athletes consumed either
the ISB (mean ± SD −0.8 ± 0.1°C) or the CLB (18.4 ± 0.5°C). Performance time was not significantly different after consuming
the ISB compared with the CLB (29.42 ± 2.07 min for ISB vs. 29.98 ± 3.07 min for CLB, P = 0.263). T
re (37.0 ± 0.3°C for ISB vs. 37.4 ± 0.2°C for CLB, P = 0.001) and physiological strain index (0.2 ± 0.6 for ISB vs. 1.1 ± 0.9 for CLB, P = 0.009) were lower at the end of recovery and before the performance trial after ingestion of the ISB compared with the
CLB. Mean thermal sensation was lower (P < 0.001) during recovery with the ISB compared with the CLB. Changes in plasma volume and the concentrations of blood variables
(i.e., glucose, lactate, electrolytes, cortisol and catecholamines) were similar between the two trials. In conclusion, ingestion
of ISB did not significantly alter exercise performance even though it significantly reduced pre-exercise T
re compared with CLB. Irrespective of exercise performance outcomes, ingestion of ISB during recovery from exercise in hot humid
environments is a practical and effective method for cooling athletes following exercise in hot environments. 相似文献
5.
Jentjens RL Cale C Gutch C Jeukendrup AE 《European journal of applied physiology》2003,88(4-5):444-452
Studies on the effect of the pre-exercise ingestion of carbohydrate on metabolism and performance have produced conflicting
results, perhaps because of differences in the designs of the studies. The purpose of the present study was to examine the
effects of ingesting differing amounts of glucose pre-exercise on the glucose and insulin responses during exercise and on
time-trial (TT) performance. Nine well-trained male cyclists completed four exercise trials separated by at least 3 days.
At 45 min before the start of exercise subjects consumed 500 ml of a beverage containing either 0 g (PLAC), 25 g (LOW), 75 g
(MED) or 200 g (HIGH) of glucose. The exercise trials consisted of 20 min of submaximal steady-state exercise (SS) at 65%
of maximal power output immediately followed by a [mean (SEM)] 691 (12) kJ TT. Plasma insulin concentrations at the onset
of exercise were significantly higher (P<0.05) in MED and HIGH compared with LOW and PLAC. Plasma glucose concentration fell rapidly (P<0.05) during SS exercise in all glucose trials, but remained steady in PLAC. No difference in plasma glucose concentration
was observed between the glucose trials at any time. Hypoglycaemia (less than 3.5 mmol·l–1) was observed in six subjects during SS but only after ingesting glucose pre-exercise. However, there was no difference in
TT performance between the four trials. The ingestion of 0, 25, 75 or 200 g of glucose 45 min before a 20 min submaximal exercise
bout did not affect subsequent TT performance. In addition, mild rebound hypoglycaemia following pre-exercise glucose ingestion
did not negatively affect performance.
Electronic Publication 相似文献
6.
Bélanger P Fillion Y Couturier K Gauthier MS Lavoie JM 《European journal of applied physiology》2003,89(1):8-13
The purpose of the present study was to assess the effects of exogenously increasing the circulating levels of glucagon on
the metabolic responses to exercise in rats. A total of six groups of rats were infused (iv) either with glucagon (20 or 50 ng·kg−1·min−1) or saline (0.9% NaCl), either in the resting state or during a bout of running exercise (45 min, 26 m·min−1, 0% grade). Blood samples were taken at the end of the 45-min experiment. Animals infused with glucagon at 50 ng·kg−1·min−1 showed significantly (P<0.01) higher mean plasma glucagon concentrations than animals infused with saline or glucagon at 20 ng·kg−1·min−1. In addition, exercise resulted in significantly (P<0.05) higher mean plasma glucagon concentrations, compared to rest, in all groups. In spite of these differences in glucagon
concentrations, there were no significant (P>0.05) effects of exercise and glucagon infusion on mean hepatic glycogen, plasma glucose, insulin, C-peptide, β-hydroxybutyrate,
or catecholamine concentrations. Although exercise resulted in a significant (P<0.01) increase in plasma glycerol and free fatty acid concentrations and a significant (P<0.05) decrease in glycogen in the soleus muscle, these responses were not affected by the glucagon infusion. These results suggest that the liver is non-responsive
to physiological hyperglucagonemia in a short-term (45 min) exercise situation.
Electronic Publication 相似文献
7.
C. J. Orok R. L. Hughson H. J. Green J. A. Thomson 《European journal of applied physiology》1989,59(4):262-267
Summary Seven trained male cyclists (
=4.42±0.23 l·min−1; weight 71.7±2.7 kg, mean ± SE) completed two incremental cycling tests on the cycle ergometer for the estimation of the
“individual anaerobic threshold” (IAT). The cyclists completed three more exercises in which the work rate incremented by
the same protocol, but upon reaching selected work rates of approximately 40, 60 and 80%
, the subjects cycled for 60 min or until exhaustion. In these constant load studies, blood lactate concentration was determined
on arterialized venous ([La−]av) and deep venous blood ([La−]v) of the resting forearm. The av-v lactate gradient across the inactive forearm muscle was −0.08 mmol·l−1 at rest. After 3 min at each of the constant load work rates, the gradients were +0.05, +0.65* and +1.60* mmol·l−1 (*P<0.05). The gradients after 10 min at these same work rates were −0.09, +0.24 and +1.03* mmol·l−1. For the two highest work rates taken together, the lactate gradient was less at 10 min than 3 min constant load exercise
(P<0.05). The [La−]av was consistently higher during prolonged exercise at both 60 and 80%
than that observed at the same work rate during progressive exercise. At the highest work rate (at or above the IAT), time
to exhaustion ranged from 3 to 36 min in the different subjects. These data showed that [La−] uptake across resting muscle continued to increase to work rates above the IAT. Further, the greater av-v lactate gradient at 3 min than 10 min constant load exercise supports the concept that inactive muscle might act as a passive
sink for lactate in addition to a metabolic site. 相似文献
8.
Mc Clean CM Mc Laughlin J Burke G Murphy MH Trinick T Duly E Davison GW 《European journal of applied physiology》2007,100(2):225-234
Oxidative stress is postulated to be responsible for the postprandial impairments in vascular function. The purpose of this
study was to measure pulse wave velocity (PWV) and markers of postprandial oxidative stress before and after an acute bout
of moderate exercise. Ten trained male subjects (age 21.5 ± 2.5 years, VO2 max 58.5 ± 7.1 ml kg−1 min−1) participated in a randomised crossover design: (1) high-fat meal alone (2) high-fat meal followed 2 h later by a bout of
1 h moderate (60% max HR) exercise. PWV was examined at baseline, 1, 2, 3, and 4 h postprandially. Blood Lipid hydroperoxides
(LOOHs), Superoxide dismutase (SOD) and other biochemical markers were measured. PWV increased at 1 h (6.49 ± 2.1 m s−1), 2 h (6.94 ± 2.4 m s−1), 3 h (7.25 ± 2.1 m s−1) and 4 h (7.41 ± 2.5 m s−1) respectively, in the control trial (P < 0.05). There was no change in PWV at 3 h (5.36 ± 1.1 m s−1) or 4 h (5.95 ± 2.3 m s−1) post ingestion in the exercise trial (P > 0.05). LOOH levels decreased at 3 h post ingestion in the exercise trial compared to levels at 3 h (P < 0.05) in the control trial. SOD levels were lower at 3 h post ingestion in the control trial compared to 3 h in the exercise
trial (0.52 ± 0.05 vs. 0.41 ± 0.1 units μl−1; P < 0.05). These findings suggest that a single session of aerobic exercise can ameliorate the postprandial impairments in
arterial function by possibly reducing oxidative stress levels. 相似文献
9.
The aim of this study was to determine the timecourse of recovery of immunoendocrine responses following prolonged cycling.
With the approval of the Ethics Committee, ten healthy men (age 21.6 ± 0.9 years, height 1.77 ± 0.01 m, body mass 66.9 ± 1.8 kg,
VO2max 54.2 ± 2.0 ml kg−1 min−1; means ± SEM) performed either a 2 h cycling trial at 55% peak aerobic power or a resting control trial in a counterbalanced
order, separated by at least 6 days. No food was consumed, though water ingestion was allowed ad libitum, until trials were
completed. Venous blood samples were collected at pre-exercise, post-exercise, and at 1, 3, 6 and 9 h post-exercise. Haematological
analysis was performed using an automated cell counter. Plasma concentrations of hormones were determined using ELISA kits.
Neutrophil degranulation (bacteria-stimulated) and oxidative burst (formyl-methionyl-leucyl-phenylalanine-induced) were measured
using an ELISA kit and a chemiluminescence assay, respectively. Results were analyzed using two-factor repeated measures ANOVA
with post hoc Tukey tests and paired t tests applied where appropriate. The main findings of this study were that, compared with the resting trial, an acute single
bout of prolonged exercise (1) decreased plasma glucose concentrations but increased circulating leukocyte, neutrophil, and
monocyte counts for 9 h; (2) increased plasma cortisol concentrations but suppressed neutrophil function on a per cell basis
for 6 h. In conclusion, the findings of this study suggest that the impact of a single bout of prolonged cycling on immunoendocrine
responses would be recovered around 9 h post-exercise at fasted status. 相似文献
10.
Plasma norepinephrine and heart rate dynamics during recovery from submaximal exercise in man 总被引:2,自引:0,他引:2
Renza Perini Claudio Orizio Alessandro Comandè Maurizio Castellano Marina Beschi Arsenio Veicsteinas 《European journal of applied physiology》1989,58(8):879-883
Summary The time course of heart rate (HR) and venous blood norepinephrine concentration [NE], as an expression of the sympathetic
nervous activity (SNA), was studied in six sedentary young men during recovery from three periods of cycle ergometer exercise
at 21%±2.8%, 43%±2.1% and 65%±2.3% of
respectively (mean±SE). The HR decreased mono-exponentially withτ values of 13.6±1.6 s, 32.7±5.6 s and 55.8±8.1s respectively in the three periods of exercise. At the low exercise level no
change in [NE] was found. At medium and high exercise intensity: (a) [NE] increased significantly at the 5th min of exercise
(Δ[NE]=207.7±22.5 pg·ml−1 and 521.3±58.3 pg·ml−1 respectively); (b) after a time lag of 1 min [NE] decreased exponentially (τ=87 s and 101 s respectively); (c) in the 1st min HR decreased about 35 beats · min−1; (d) from the 2nd to 5th min of recovery HR and [NE] were linearly related (100 pg·ml−1
Δ[NE]5 beats ·min−1). In the 1st min of recovery, independent of the exercise intensity, the adjustment of HR appears to have been due mainly
to the prompt restoration of vagal tone. The further decrease in HR toward the resting value could then be attributed to the
return of SNA to the pre-exercise level. 相似文献
11.
Summary Muscle force recovery from short term intense exercise was examined in 16 physically active men. They performed 50 consecutive
maximal voluntary knee extensions. Following a 40-s rest period five additional maximal contractions were executed. The decrease
in torque during the 50 contractions and the peak torque during the five contractions relative to initial torque were used
as indices for fatigue and recovery, respectively. Venous blood samples were collected repeatedly up to 8 min post exercise
for subsequent lactate analyses. Muscle biopsies were obtained from m. vastus lateralis and analysed for fiber type composition,
fiber area, and capillary density.
Peak torque decreased 67 (range 47–82%) as a result of the repeated contractions. Following recovery, peak torque averaged
70 (47–86%) of the initial value.
Lactate concentration after the 50 contractions was 2.9±1.3 mmol·l−1 and the peak post exercise value averaged 8.7±2.1 mmol·l−1. Fatigue and recovery respectively were correlated with capillary density (r=−0.71 and 0.69) but not with fiber type distribution. A relationship was demonstrated between capillary density and post
exercise/peak post exercise blood lactate concentration (r=0.64). Based on the present findings it is suggested that lactate elimination from the exercising muscle is partly dependent
upon the capillary supply and subsequently influences the rate of muscle force recovery.
Dr. Tesch was on leave from Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden 相似文献
12.
The purpose of this study was to investigate the effects of exercise intensity on the magnitude of acute post-exercise hypotension
while controlling for total work done over the exercise bout. Seven normotensive physically active males aged 28 ± 6 years
(mean ± SD) completed four experimental trials, a no exercise control, 30 min of semi-recumbent cycling at 70%
(INT), cycling for 30 min at 40% (SMOD) and cycling at 40% for a time which corresponded to the same total work done as in the intense trial (LMOD). Blood pressure (BP), heart rate,
stroke volume, cardiac output, total peripheral resistance, core body temperature and forearm skin and limb blood flow were
measured prior to and for 20 min following the exercise bout. Post-exercise summary statistics were compared between trials
with a one-factor general linear model. The change in systolic BP, averaged over the 20-min post-exercise period was significantly
lower only following the INT (−5 ± 3 mm Hg) and LMOD exercise (−1 ± 7 mm Hg) compared to values in control (P < 0.04). The changes in systolic BP and MAP following INT and LMOD were not significantly different from each other (P > 0.05). Similar results were obtained when the minimum values of these variables recorded during the post-exercise period
were compared. Mean changes in cardiac output (1.9 ± 0.3 l min−1) and total peripheral resistance (−3 ± 1 mm Hg l−1 min−1) after INT exercise were also different from those in CON (P < 0.0005). The acute post-exercise reduction in BP was clinically similar following high intensity short duration exercise
and moderate intensity longer duration exercise that was matched for total work done. 相似文献
13.
The effect of citrate loading on exercise performance,acid-base balance and metabolism 总被引:1,自引:0,他引:1
John M. Kowalchuk Stephen A. Maltais Keiji Yamaji Richard L. Hughson 《European journal of applied physiology》1989,58(8):858-864
Summary Nine subjects (
65±2 ml·kg−1·min−1, mean±SEM) were studied on two occasions following ingestion of 500 ml solution containing either sodium citrate (C, 0.300
g·kg−1 body mass) or a sodium chloride placebo (P, 0.045 g·kg−1 body mass). Exercise began 60 min later and consisted of cycle ergometer exercise performed continuously for 20 min each
at power outputs corresponding to 33% and 66%
, followed by exercise to exhaustion at 95%
. Pre-exercise arterialized-venous [H+] was lower in C (36.2±0.5 nmol·l−1; pH 7.44) than P (39.4±0.4 nmol·l−1; pH 7.40); the plasma [H+] remained lower and [HCO
3
−
] remained higher in C than P throughout exercise and recovery. Exercise time to exhaustion at 95%
was similar in C (310±69 s) and P (313±74 s). Cardiorespiratory variables (ventilation,
,
, heart rate) measured during exercise were similar in the two conditions. The plasma [citrate] was higher in C at rest (C,
195±19 μmol·l−1; P, 81±7 μmol·l−1) and throughout exercise and recovery. The plasma [lactate] and [free fatty acid] were not affected by citrate loading but
the plasma [glycerol] was lower during exercise in C than P. In conclusion, sodium citrate ingestion had an alkalinizing effect
in the plasma but did not improve endurance time during exercise at 95%
. Furthermore, citrate loading may have prevented the stimulation of lipolysis normally observed with exercise and prevented
the stimulation of glycolysis in muscle normally observed in bicarbonate-induced alkalosis. 相似文献
14.
The glycaemic and insulinaemic responses to different carbohydrates vary and these have been suggested to affect performance.
The purpose of the present study was to determine the effects of pre-exercise ingestion of glucose (GLU), galactose (GAL)
and trehalose (TRE) on metabolic responses at rest and during exercise and on subsequent time-trial (TT) performance. Eight
well-trained male cyclists completed three exercise trials separated by at least 3 days. At 45 min before the start of exercise
subjects consumed 500 ml of a beverage containing 75 g of either glucose, galactose or trehalose. The exercise trials consisted
of 20 min of submaximal steady-state exercise (SS) at 65% of maximal power output immediately followed by a [mean (SEM)] 702 (25) kJ
TT. Plasma glucose concentration 15 min postprandial was significantly higher in GLU compared to GAL and TRE (P<0.05). This was accompanied by a more than twofold greater rise in plasma insulin concentration in GLU compared to GAL and
TRE (118% and 145%, respectively). During SS exercise four subjects in GLU and one subject in TRE developed a rebound hypoglycaemia
(plasma glucose concentration less than 3.5 mmol·l–1). No differences were observed in TT performance between the three trials. Pre-exercise ingestion of trehalose and galactose
resulted in lower plasma glucose and insulin responses prior to exercise and reduced the prevalence of rebound hypoglycaemia.
Despite the attenuated insulin and glucose responses at rest and during exercise following pre-exercise ingestion of galactose
and trehalose, there was no difference in TT performance compared with pre-exercise ingestion of glucose.
Electronic Publication 相似文献
15.
J. P. Kirwan P. M. Clarkson J. E. Graves P. L. Litchfield W. C. Byrnes 《European journal of applied physiology》1986,55(3):330-333
Summary The purpose of this study was to measure serum creatine kinase (CK) activity and serum myoglobin (MG) concentrations in women
after two unilateral isometric knee extension exercises. Forty maximal voluntary contractions (MVC) were held for 10 s, with
either a 5 s (10∶5) or 20 s 10∶20 exercise (349.4±66.1 mU · ml−1) and 6 h and MG values were measured pre, 0, 3, 6, and 18 h post exercise. For CK, the highest post exercise values were
observed at 6 h following the 10∶20 exercise (349.4±66.1 mU · ml−1) and 6 h following the 10∶5 exercise (194.1±18.6 mU · ml−1). For MG, the highest values were found 3 h after the 10∶20 exercise (148.9±61.7 ng · ml−1) and 6 h after the 10∶5 exercise (67.3±10.9 ng · ml−1). Serum CK and MG levels were significantly greater (p<0.01) after the 10∶20 exercise bout. The data demonstrate that CK and MG values for women increase significantly after isometric
exercise. Since greater tension levels were maintained during the 10∶20 exercise it is hypothesized that increased serum CK
and MG values after isometric exercise may be related to the tension generated by the contracting muscle. 相似文献
16.
Roger A. Fielding William J. Evans Virginia A. Hughes Lyle L. Moldawer Bruce R. Bistrian 《European journal of applied physiology》1986,55(5):482-485
Summary Alpha-ketoisocaproic acid (KIC) is the product of the transamination of the indispensable amino acid leucine, which is the
first step in the complete degradation of leucine. To determine the effects of intense exercise on muscle and blood levels
of KIC, 7 male volunteers performed cycle exercise to exhaustion. After pedaling at an intensity of 90 W for 3 min, the load
was increased by 60 W every 3 min until volitional fatigue. Muscle biopsies were obtained prior to and immediately after exercise
and rapidly frozen for later determination of KIC. During exercise, blood lactate levels increased as expected, while plasma
KIC levels did not change. Following exercise, plasma KIC levels rose significantly with peak values occurring 15 min after
exercise and did not return to pre-exercise values until 60 min after exercise. In contrast, muscle KIC levels increased during
exercise from a pre-exercise mean of 49.4±4.1 Μmol · kg−1 wet wt to 78.1±6.5 Μmol · kg−1 after exercise, an average increase of 48% (P<0.05). These data indicate that during intense exercise, leucine transamination in muscle may continue at a faster rate than
the decarboxylation of KIC. In addition, plasma levels of KIC did not reflect the intracellular accumulation of KIC during
exercise, suggesting a delay in the diffusion of KIC from muscle. 相似文献
17.
Demura S Morishita K Yamada T Yamaji S Komatsu M 《European journal of applied physiology》2011,111(11):2837-2843
l-Ornithine plays an important role in ammonia metabolism via the urea cycle. This study aimed to examine the effect of l-ornithine hydrochloride ingestion on ammonia metabolism and performance after intermittent maximal anaerobic cycle ergometer
exercise. Ten healthy young adults (age, 23.8 ± 3.9 year; height, 172.3 ± 5.5 cm; body mass, 67.7 ± 6.1 kg) with regular training
experience ingested l-ornithine hydrochloride (0.1 g/kg, body mass) or placebo after 30 s of maximal cycling exercise. Five sets of the same maximal
cycling exercise were conducted 60 min after ingestion, and maximal cycling exercise was conducted after a 15 min rest. The
intensity of cycling exercise was based on each subject’s body mass (0.74 N kg−1). Work volume (watt), peak rpm (rpm) before and after intermittent maximal ergometer exercise and the following serum parameters
were measured before ingestion, immediately after exercise and 15 min after exercise: ornithine, ammonia, urea, lactic acid
and glutamate. Peak rpm was significantly greater with l-ornithine hydrochloride ingestion than with placebo ingestion. Serum ornithine level was significantly greater with l-ornithine hydrochloride ingestion than with placebo ingestion immediately and 15 min after intermittent maximal cycle ergometer
exercise. In conclusion, although maximal anaerobic performance may be improved by l-ornithine hydrochloride ingestion before intermittent maximal anaerobic cycle ergometer exercise, the above may not depend
on increase of ammonia metabolism with l-ornithine hydrochloride. 相似文献
18.
Carbohydrate supplementation during prolonged cycling exercise spares muscle glycogen but does not affect intramyocellular lipid use 总被引:1,自引:0,他引:1
Stellingwerff T Boon H Gijsen AP Stegen JH Kuipers H van Loon LJ 《Pflügers Archiv : European journal of physiology》2007,454(4):635-647
Using contemporary stable-isotope methodology and fluorescence microscopy, we assessed the impact of carbohydrate supplementation
on whole-body and fiber-type-specific intramyocellular triacylglycerol (IMTG) and glycogen use during prolonged endurance
exercise. Ten endurance-trained male subjects were studied twice during 3 h of cycling at 63 ± 4% of maximal O2 uptake with either glucose ingestion (CHO trial; 0.7 g CHO kg−1 h−1) or without (CON placebo trial; water only). Continuous infusions with [U-13C] palmitate and [6,6-2H2] glucose were applied to quantify plasma free fatty acids (FFA) and glucose oxidation rates and to estimate intramyocellular
lipid and glycogen use. Before and after exercise, muscle biopsy samples were taken to quantify fiber-type-specific IMTG and
glycogen content. Plasma glucose rate of appearance (R
a) and carbohydrate oxidation rates were substantially greater in the CHO vs CON trial. Carbohydrate supplementation resulted
in a lower muscle glycogen use during the first hour of exercise in the CHO vs CON trial, resulting in a 38 ± 19 and 57 ± 22%
decreased utilization in type I and II muscle-fiber glycogen content, respectively. In the CHO trial, both plasma FFA R
a and subsequent plasma FFA concentrations were lower, resulting in a 34 ± 12% reduction in plasma FFA oxidation rates during
exercise (P < 0.05). Carbohydrate intake did not augment IMTG utilization, as fluorescence microscopy revealed a 76 ± 21 and 78 ± 22%
reduction in type I muscle-fiber lipid content in the CHO and CON trial, respectively. We conclude that carbohydrate supplementation
during prolonged cycling exercise does not modulate IMTG use but spares muscle glycogen use during the initial stages of exercise
in endurance-trained men. 相似文献
19.
P. Pilardeau J. -P. Richalet P. Bouissou J. Vaysse P. Larmignat A. Boom 《European journal of applied physiology》1990,59(6):450-453
Summary The effects of acute hypoxia (2 days at 4350 m) on whole saliva flow and composition were studied on 12 sea-level natives,
at rest and following a maximal exercise. Exercise, performed in normoxia and hypoxia, did not induce variations in saliva
flow rate, saliva potassium or α-amylase concentrations. In contrast, acute hypoxia did lead to an increase in mean saliva
flow rate both at rest (0.63 ml·min−1 to 0.93 ml·min−1,P<0.01) and after exercise (0.56 ml·min−1 to 1.06 ml·min−1,P<0.05) and a decrease in mean saliva potassium concentration at rest (20.8 mmol·1−1 to 14.7 mmol·1−1,P<0.01) as well as after exercise (21.7 mmol·1−1 to 16.5 mmol·1−1,P<0.05). This effect might be the consequence of a hypoxia-induced stimulation of the parasympathetic nervous system. 相似文献
20.
<Emphasis Type="Italic">V</Emphasis>O<Subscript>2</Subscript>max during successive maximal efforts 总被引:1,自引:0,他引:1
Foster C Kuffel E Bradley N Battista RA Wright G Porcari JP Lucia A deKoning JJ 《European journal of applied physiology》2007,102(1):67-72
The concept of VO2max has been a defining paradigm in exercise physiology for >75 years. Within the last decade, this concept has been both
challenged and defended. The purpose of this study was to test the concept of VO2max by comparing VO2 during a second exercise bout following a preliminary maximal effort exercise bout. The study had two parts. In Study #1,
physically active non-athletes performed incremental cycle exercise. After 1-min recovery, a second bout was performed at
a higher power output. In Study #2, competitive runners performed incremental treadmill exercise and, after 3-min recovery,
a second bout at a higher speed. In Study #1 the highest VO2 (bout 1 vs. bout 2) was not significantly different (3.95 ± 0.75 vs. 4.06 ± 0.75 l min−1). Maximal heart rate was not different (179 ± 14 vs. 180 ± 13 bpm) although maximal V
E was higher in the second bout (141 ± 36 vs. 151 ± 34 l min−1). In Study #2 the highest VO2 (bout 1 vs. bout 2) was not significantly different (4.09 ± 0.97 vs. 4.03 ± 1.16 l min−1), nor was maximal heart rate (184 + 6 vs. 181 ± 10 bpm) or maximal V
E (126 ± 29 vs. 126 ± 34 l min−1). The results support the concept that the highest VO2 during a maximal incremental exercise bout is unlikely to change during a subsequent exercise bout, despite higher muscular
power output. As such, the results support the “classical” view of VO2max. 相似文献